1. Field of the Invention
The invention generally relates to a television system and more particularly to a system for and method of identifying a part (clip) of a video stream, the system and method being difficult to use for a commercial cutting function. The system and the method is applicable to a television system that permits the user to collect a variety of video clips such as program previews, commercials, representative scenes of a program and so on.
2. Description of the Prior Art
Recently, television (TV) broadcasting systems have increased channels in number. This often causes the user to find a difficulty in selecting programs to watch. In order to facilitate the selection of programs, broadcasting parties deliver program presentation scenes, program previews and so on between programs. Engineers of next generation broadcasting system are examining video environment in which the receiver automatically stores incoming program presentation scenes so as to enable the user to select programs meeting the user""s taste without suffering from a flood of information. These environments will permit the user to search the stored program presentation scenes for favorite programs. In these environments, a television receiver can automatically record a highlight scene in each program, permitting the user to find a program he or she want by searching the recorded scenes. Also, if the user likes automobiles for example, he or she can control the television receiver to automatically accumulate commercials of automobiles to form a visual catalogue of automobiles.
The receiver automatically accumulating only particular programs or particular scenes is achieved by the broadcasting side attaching identifying codes to broadcast programs and scenes and by the receiver identifying desired programs and scenes through the identifying codes. Specifically, the broadcasting side attaches tags to parts of a transmitted video stream such as e.g., program presentation scenes, commercials and program previews (i.e., includes in the transmitted video stream a tag or data set for each video part spacing a predetermined fixed period or a period specified in the tag after the video part). This enables the receiver to identify the video part by using associated tags, permitting the receiver to accumulate desired ones of the tagged scenes.
However, these tags also permit the receiver to easily remove or cut commercials and program presentation scenes inserted in the program in itself (commercial cutting). This is vary disadvantageous for the sponsors to the program.
It is an object of the invention to provide techniques for collecting desired parts or scenes of a video stream by attaching a tag to each of the desired parts so as to prevent the tags from being used for commercial cutting (or information deletion, from the video stream, based on the tags associated with the commercial scenes).
According to the principles of the invention, a method of and system for collecting a tagged scene of a video stream transmitted from a first station to second stations in television broadcasting system while preventing tags from being used for commercial cutting (i.e., indiscriminate tagged scene cutting) is provided. The first station generates a tag for the scene. The tag includes a category of the scene, a location for use in locating a beginning of the scene and a length of the scene. The first station makes an arrangement to prevent the tag from being used for commercial cutting; and insert the tag in the video stream at the position located by using the location.
The location in time may be either an interval between the insertion of the tag and the transmission of the scene or a relative time with respect to a reference time. The location may be a fixed period.
A second station obtains a desired category from the user; detects a tag in the video stream; makes a test to see if the category coincides with the desired category; and if so, clipping from the video stream a part of a length defined by the length of the scene from a position located by using the location in such manner as accords with the arrangement.
In a first embodiment, the length information is removed from the tag. In this case, the second station clips a largest one of a plurality of standardized lengths.
In a second embodiment one or more counterfeit tag is inserted in the video stream. The counterfeit tags includes false data.
In a third, the first station encodes one of the category, the location and the length through a one-way function and uses the encoded one in place of the original one. The second station decodes the encoded one into a decoded one and uses the decoded one.
In a fourth embodiment, for each of possible categories the first station further sends a set of the category and the encoded category to the second stations before inserting the tag. The second station receives the sets from the first station; and if the category of the detected tag coincides with the encoded category associated by the set with the desired category, clips the above-mentioned part from the video stream.
In a fifth embodiment, a syndrome of a combination of the category and a parameter is used as the encoded category. In the first station, a list of subcategories is made for a desired one of possible categories; a syndrome for a combination of the desired category and each of the subcategories is calculated by using each of the subcategories as the parameter; a table of the category, the subcategories, and corresponding syndromes is sent to the second stations. The second station stores the received table and uses the syndromes as the encoded categories and the subcategories as the categories.
Also, the first station may create a super-category comprising a list of categories; find a syndrome for a combination of the super-category and each of the categories of the list by using each of the categories of the list as the parameter; send the list for the super-category to the second stations; and use the syndromes as the encoded categories.